Firearm and alloy for making same



FRANK A. FAHRENWALD; or CLEVELAND HEIGHTS, OHIO.

FIREARM AND ALLOY FOR MAKING SAME.

No Drawing.

To all whom it may concern:

Be it known that I, FRANK A; FAHREN- WALD, a citizen of the UnitedStates, re siding at Cleveland-Heights,in the county of Cuyahoga andState of Ohio, have invented-a certain new and .useful Improvement inFirearms and Alloys for Making Same, of which the following is a full,clear, and exact description.

This invention relates to firearms and ordnance and has for its object aprovision of metallic alloy for use in construction of the same whichshall be more resistant to corrosion by the combustion products of theexplosives as well as less effected by atmospheric conditions and saltsolutions (such as sea water or perspiration) than any of the materialsnow in use vfor the purpose; which shall be at least as easilymanufactured as the steels at present employed, which shall be at leastequally resistant with steel to mechanical erosion and less subject thansteel to becoming fouled by the material of the bullets or projectilesemployed; and which shall not be unduly high in intrinsic value.

Practically the only substance now in use for the barrels of firearmsand ordnance is some kind of a steel, in otherwords contains aconsiderable percentage of carbon in the form of iron carbid dissolvedin' an excess of iron. This is sometimes modified;- by the presence of avery small percenta e of nickel, vanadium, tungsten, etc., but t eessential characteristics are, those of steel,

which includethe capacity of becoming hardened by heating and quenchingtogether with high susceptibility to the 'corro-- sive effect of powderr gases, powder re,- sidues, salt solutions and other rusting conditions. Furthermore such carbids are seldom disseminated withperfectuniformity throughout the mass of material, 'andbesides, owing totheir susceptibility to temperature influences, it is seldom that. allparts are giyen the same degree of hardness or temper which produces ityof strain within the material. The consequence is that when a barrel ofsteel is bored, the effect of the perforation is to release this strainunequally in different parts of the barrel which therefore auto--matically bends in one direction or the other as a result of the borinoperation alone and hence requires a care 1 stralghtenmg op-Specification of Letters Patent.

' nickel, possesses resistivity an inequal- Patented July 13, 1 920.

Applicationvfiled December 15, 1919. Serial Nol 345,083.

eration which is a task fit only for the most expert of workmen. such abarrel when-heated by repeated firing always becomes Warped and thuspro-,

duces a deflection of the bullet depending upon the temperature.

According to my invention I avoid the faults due to thesecharacteristics of steel by reducing the carbon content to the lowest,possible extent, and secure the necessary hardness and toughness of themetal by the use of some substance other than carbon which shall havethe added capability of shielding the fundamental metal againstcorrosive action. Owing. to 1ts cheapness Furthermore and availability Iprefer to employ iron as the fundamental metal, although other metals ofthe iron group can equally be employed, and'in fact. serve the purposeto a degree even superior to iron, although the iron-base alloy issufiicient for every practical purpose. The two' basic protective metalsfor use with iron are chromium and nickel. They 'may be used either,separately, or together, either with or without other substances. Analloy of iron with 10% of either of the metals, chromium or to corrodinginfluences farsuperior to anything hereto-.

fore used in firearms as also does an alloy of iron combined with bothchromium and than in the case of an alloy not containing.

these ingredients and as a result it is neces- "nickel up to thispercentage, the latter ocsary to keep the amount of carbon very low. .2of 1% appears to be about the uppermost desirable limit of carbon, andwith the higher percentages of either or bothof the'metals, nickel orchromium, the carbon ought to be retained below about .1 of 1%. Thenecessary hardness in .the alloy is se vcured by either. nickel orchromium inamounts of 10% "or upward and these amounts: also affordmarked chemical re- 'sistivity, The upper limit of chromium is about 25%since above this amount the alloy becomes too hard for convenientfabricating, there is no limit upon the proportion of nickel other thaneconomic considerations.

These alloys can readily be'macle in the 2 v i,sae,ioi

electric furnace by rifled and otherwise fabricated with the samefacility as steel. Barrels made of the same do not require 'to bestraightened after boring as in the case of steel and do not show anytendency v to deflection upon heating. The surface of the metal tends tobecome smoother and more polished the more frequently it is fired and.offers far less tendency than steel barrels to become fouled or erodedby the material of the projectiles; barrels containing upward of about10% of chromium are highly immune to gases and residues of allexplosives, even when left uncleaned for long periods, while chromiumalloys above about 12% are completely immune. Barrels of iron alloyedwith 30% or more of nickel will withstand severe neglect and alloyscontaining 15% of nickel together with 10% of chromium are entirelyimmuned.

10% of nickel is not enough to confer highv immunity for barrel use, butproduces an Y alloy which is excellent for breech blocks,

actions, etc., since it is markedly resistant to atmospheric influences.i

There are other metals than nickel or chromium which will exert aprotective effect upon iron together with the hardening effect madenecessary by the reduction in carbon content, but suffer thedisadvantage either of requiring undue amounts to con fer equal chemicalresistivity or exert i-njurious effects upon the physical propertieswhen employed to a suflicient extent to produce by themselves thedesired protection effect. Cobalt is the full "equivalent of nickel inthis relation but is ofwless practical value because of itscomparatively high cost. Small'quantities of vanadium, titanium, or

manganese are very the use of pure mate; rials and can be melted, cast,forged, drilled,

I 1 signature. desirable for use as scavengers and the presence of smallamounts of vanadium or manganese in the finishedalloy is an advantagebut titanium or zirconium, if used as scavengers should be restricted tothe' exact amount which will be eliminated inprocess unless carbon andsilicon are substantially entirely eliminated. These substances are tobe used in addition to the'nickel or chronium and not in substitutiontherefor, wherefore I consider the preferable alloy to be essentiallythat of .iron with either or both nickel and (or) chromium, the highestlimit of chromium beingabout 25 and the highest limit of Qiron about 90,and the lowest limit of nickel or chromium or some combination of the 7two being about 10%.

While I'have suggested this principally in connection with the barrelsof firearms I do not exclude its use for breech blocks, firingmechanisms, etc.,*"wh-ioh parts are also subjected to some extent topowder fumes and residues and to an equal or greater extent toatmospheric and salt conditions.

Having thus described my invention, what Iclaim is:

1. A firearm barrel made of an alloy containing iron combined with atleast about thirty per cent. of one or more other metals of the irongroup. I 4

2. A firearm barrel made of an alloy conthat the .total amount .ofnon-ferrous metal in the alloy shall constitute about t'wenty- I fiveper cent. of the whole, and the chromium constituting at leastabout fiveper cent. of the whole.

In testimony whereof,\l hereunto affix my FRANK A. FAHRENWALD.

